I had a book in the past giving me the significance of the alloy numbers often given in the alloy mix of aluminum & steel...

we often here 6160, 7150,4130...bla bla
each # represents an element and its concentration

but which order is which?

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It doesn't work that way, the alloy designations are just that numbers that were registered with an international body by the comapny that developed a specific alloy.

Your are going to have to look up seperate alloy concentration tables for both Aluminium alloys, Low alloy Steel, and Stainless Steels. ect. These are pretty easy to find with google.

The one element that can be tracked with the Alloy designation number is "Carbon" for Low Alloy Steels sometimes also refered to as Carbon Steels.

The last two numbers in the grade ie. " 40" in 4340 gives the Carbon content of the steel so in this case the Carbon value would be 0.40%. with a +/- tolerance of 0.05%

Basically one general rule of thumb is that as the Alloy designation numbers go lower the alloys tend to have less alloyed elements present. ie "1000" series Aluminium or Steels are very high in Al and Fe respectively.

It doesn't work that way, the alloy designations are just that numbers that were registered with an international body by the comapny that developed a specific alloy.

Your are going to have to look up seperate alloy concentration tables for both Aluminium alloys, Low alloy Steel, and Stainless Steels. ect. These are pretty easy to find with google.

The one element that can be tracked with the Alloy designation number is "Carbon" for Low Alloy Steels sometimes also refered to as Carbon Steels.

The last two numbers in the grade ie. " 40" in 4340 gives the Carbon content of the steel so in this case the Carbon value would be 0.40%. with a +/- tolerance of 0.05%

Basically one general rule of thumb is that as the Alloy designation numbers go lower the alloys tend to have less alloyed elements present. ie "1000" series Aluminium or Steels are very high in Al and Fe respectively.

Another thing of note: With aluminum, the first number is the "series" and this designates the most common alloying element. Most alloys in the same series will behave very similarly. The only large exception I can think of is 7005. It's weldable while other 7000 series are not.

Basically, you have too look them up. There are only a handful of commonly used ones. If you work with them for a while, you'll get them all memorized.

Sorry for the confusion I will try to clarify...
Within a similar group of steel alloys such as 41xx the last two digits relate to the Carbon content in tenths of a %. So a 4130 has a Carbon content of 0.30 %.

Now the first two numbers in the "41"30 do not directly relate to any specific element composition but generally lower numbers here specify groups of alloys that have a higher Iron " Fe " content and less of the other alloying elements such as Nickel, Chromium and Molybdenum etc.

Example a grade 1035 Steel has the same Carbon content as a grade 4135 but the 1035 has lower levels of the alloying elements mentioned above and will therefore have different physical properties as well.

Usually increasing the Carbon content hardens the steel.

Generally 1XXX series Steels are often called Low Alloy Steels, While 4XXX and 8XXX are Medium Alloy .

Stainless Steels have much higher levels of Nickel and Chromium- 20 % or more and are therefore called High Alloy steels. They have seperate designation scheme for these that use a three number system ie. 304, 316 and 317 etc. to specify chemical ranges of the alloying elements present.

only 2,6,7 can be heat treated T-6 being the most common heat treatement

what you say now?

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Yup, that is correct, of course this only relates to Aluminium aloys and not Steels which is what I was discussing in the last post.

Also don't forget just to complicate matters more the above only deals with Aluminium wrought alloys all other casting alloys use another completely different numbering system with three digit numbers such as # 356, 380 etc. which are also common casting alloys for the automotive industry